[PATCH 08/11] xfs_scrub: enforce read verify pool minimum io size

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

Make sure we always issue media verification requests aligned to the
minimum IO size that the caller cares about.  Concretely, this means
that we only care about doing IO in filesystem block-sized chunks.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 scrub/read_verify.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)


diff --git a/scrub/read_verify.c b/scrub/read_verify.c
index 7cfe834c..7cac0a0f 100644
--- a/scrub/read_verify.c
+++ b/scrub/read_verify.c
@@ -77,6 +77,15 @@ read_verify_pool_alloc(
 	struct read_verify_pool		*rvp;
 	int				ret;
 
+	/*
+	 * The minimum IO size must be a multiple of the disk sector size
+	 * and a factor of the max io size.
+	 */
+	if (miniosz % disk->d_lbasize)
+		return EINVAL;
+	if (RVP_IO_MAX_SIZE % miniosz)
+		return EINVAL;
+
 	rvp = calloc(1, sizeof(struct read_verify_pool));
 	if (!rvp)
 		return errno;
@@ -245,6 +254,11 @@ read_verify_schedule_io(
 	int				ret;
 
 	assert(rvp->readbuf);
+
+	/* Round up and down to the start of a miniosz chunk. */
+	start &= ~(rvp->miniosz - 1);
+	length = roundup(length, rvp->miniosz);
+
 	rv = ptvar_get(rvp->rvstate, &ret);
 	if (ret)
 		return ret;